From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Summary of experimental results for a 20 HP carburetter with various modifications.
| Identifier | WestWitteringFiles\O\2January1926-March1926\ Scan124 | |
| Date | 15th January 1925 guessed | |
| contd :- -5- 20 HP. CARBURETTER WITH LIGHT AIR VALVE. The carburetter fitted with the aluminium air valve gave no appreciable difference in power to the standard brass valve - as we should expect when considering the results of the other experiments. We are still engaged in working on this instrument with regard to the metering and its characteristics will be supplied in another report. SUMMARY. The experimental results give us the following information. THROTTLE & INDUCTION PASSAGE. Increasing the size of these to 1.500" diameter does not result in an increase of power relative to standard. The metal thickness between the cylinder bores and the induction passage with the large diameter is .075" and makes casting more difficult. CARBURETTER THROAT SIZE. By increasing the throat size we get only a very small increase in power - 2½% increase of power for 57% increase of effective throat area. Increasing the high speed throat results in impairing the metering of the carburetter at low depressions. DIFFUSER JET FOR HIGH SPEED THROAT. This jet gives no appreciable improvement in power although slightly better efficiency is obtainable with weak mixtures. This however is outside the range contd :- | ||